Method and apparatus for downlink retransmission under unreliable code block group (CBG) level feedback

1. A method for wireless communication operable at a user equipment (UE), comprising:

in a first slot, transmitting a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receiving downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generating a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determining that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC;

wherein the first concatenation of CBG feedbacks comprises a first bitmap as decoded by the BS corresponding to the first set of CBGs, each bit of the first bitmap indicating an acknowledgement (ACK) or negative acknowledgement (NACK) of a corresponding CBG of the first set of CBGs, and

wherein the first concatenation of CBG feedbacks further comprises a second bitmap as decoded by the BS corresponding to a second set of CBGs transmitted by the BS prior to the first set of CBGs, each bit of the second bitmap indicating the ACK or NACK of a corresponding CBG of the second set of CBGs.

2. A method for wireless communication operable at a user equipment (UE), comprising:

in a first slot, transmitting a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receiving downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generating a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determining that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC;

wherein the second concatenation of CBG feedbacks comprises a first bitmap transmitted by the UE corresponding to the first set of CBGs, each bit of the first bitmap indicating an acknowledgement (ACK) or negative acknowledgement (NACK) of a corresponding CBG of the first set of CBGs; and

wherein the second concatenation of CBG feedbacks further comprises a second bitmap transmitted by the UE corresponding to a second set of CBGs transmitted by the BS prior to the first set of CBGs, each bit of the second bitmap indicating the ACK or NACK of a corresponding CBG of the second set of CBGs.

3. The method of claim 2 , wherein the determining that the BS correctly decoded the first CBG feedback, comprises:

scrambling the second CRC with a concatenation of the first bitmap and the second bitmap;

comparing the first CRC and the second CRC; and

if the first CRC and the second CRC match, determining that the BS correctly decoded the first CBG feedback.

4. The method of claim 3 , wherein the scrambling the second CRC comprises:

generating a random sequence using a seed based on the first bitmap and the second bitmaps; and

scrambling the second CRC with the random sequence.

5. A method for wireless communication operable at a user equipment (UE), comprising:

in a first slot, transmitting a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receiving downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generating a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determining that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC; and

generating the second concatenation of CBG feedbacks, excluding a bitmap comprising only bits that indicate negative acknowledgement (NACK) of a plurality of CBGs.

6. A method for wireless communication operable at a user equipment (UE), comprising:

in a first slot, transmitting a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receiving downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generating a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determining that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC;

scrambling the second CRC by a third concatenation of CBG feedbacks that is different from the second concatenation of CBG feedbacks; and

if the first CRC matches the second CRC, determining that the BS correctly decoded the first CBG feedback.

7. The method of claim 6 , further comprising:

determining that the BS correctly decoded the first CBG feedback when the first CRC matches the second CRC without scrambling with the second concatenation of CBG feedbacks.

8. A user equipment (UE) comprising:

a communication interface configured for wireless communication;

a memory; and

a processor operatively coupled with the communication interface and the memory,

wherein the processor and the memory are configured to:

in a first slot, transmit a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receive downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generate a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determine that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC;

wherein the first concatenation of CBG feedbacks comprises a first bitmap as decoded by the BS corresponding to the first set of CBGs, each bit of the first bitmap indicating an acknowledgement (ACK) or negative acknowledgement (NACK) of a corresponding CBG of the first set of CBGs, and

wherein the first concatenation of CBG feedbacks further comprises a second bitmap as decoded by the BS corresponding to a second set of CBGs transmitted by the BS prior to the first set of CBGs, each bit of the second bitmap indicating the ACK or NACK of a corresponding CBG of the second set of CBGs.

9. A user equipment (UE) comprising:

a communication interface configured for wireless communication;

a memory; and

a processor operatively coupled with the communication interface and the memory,

wherein the processor and the memory are configured to:

in a first slot, transmit a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receive downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generate a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determine that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC;

wherein the second concatenation of CBG feedbacks comprises a first bitmap transmitted by the UE corresponding to the first set of CBGs, each bit of the first bitmap indicating an acknowledgement (ACK) or negative acknowledgement (NACK) of a corresponding CBG of the first set of CBGs, and

wherein the second concatenation of CBG feedbacks further comprises a second bitmap transmitted by the UE corresponding to a second set of CBGs transmitted by the BS prior to the first set of CBGs, each bit of the second bitmap indicating the ACK or NACK of a corresponding CBG of the second set of CBGs.

10. The UE of claim 9 , wherein the processor and the memory are further configured to determine that the BS correctly decoded the first CBG feedback, by:

scrambling the second CRC with a concatenation of the first bitmap and the second bitmap;

comparing the first CRC and the second CRC; and

if the first CRC and the second CRC match, determining that the BS correctly decoded the first CBG feedback.

11. The UE of claim 10 , wherein the processor and the memory are further configured to scramble the second CRC, by:

generating a random sequence using a seed based on the first bitmap and the second bitmaps; and

scrambling the second CRC with the random sequence.

12. A user equipment (UE) comprising:

a communication interface configured for wireless communication;

a memory; and

a processor operatively coupled with the communication interface and the memory,

wherein the processor and the memory are configured to:

in a first slot, transmit a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receive downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generate a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determine that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC; and

generate the second concatenation of CBG feedbacks, excluding a bitmap comprising only bits that indicate negative acknowledgement (NACK) of a plurality of CBGs.

13. A user equipment (UE) comprising:

a communication interface configured for wireless communication;

a memory; and

a processor operatively coupled with the communication interface and the memory,

wherein the processor and the memory are configured to:

in a first slot, transmit a first code block group (CBG) feedback corresponding to a first set of code block groups (CBGs) received from a base station (BS);

in a second slot after the first slot, receive downlink control information (DCI) and a first cyclic redundancy check (CRC), the first CRC generated based on the DCI and further scrambled by a first concatenation of CBG feedbacks as decoded by the BS, wherein the first concatenation of CBG feedbacks comprise CBG feedbacks respectively corresponding to a plurality of slots;

generate a second CRC based on the DCI and further scrambled by a second concatenation of CBG feedbacks including the first CBG feedback;

determine that the BS correctly decoded the first CBG feedback based on a comparison of the first CRC and the second CRC;

scramble the second CRC by a third concatenation of CBG feedbacks that is different from the second concatenation of CBG feedbacks; and

if the first CRC matches the second CRC, determining that the BS correctly decoded the first CBG feedback.

14. The UE of claim 13 , wherein the processor and the memory are further configured to:

determine that the BS correctly decoded the first CBG feedback when the first CRC matches the second CRC without scrambling with the second concatenation of CBG feedbacks.